Dialogue Completion: Deep-sea Bioluminescence
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44. Student: - Why do certain deep-sea fish have glowing parts on their bodies in the complete darkness of the ocean? Teacher: - This is called bioluminescence. It is mainly used to attract prey or to find a mate in an environment where there is zero sunlight. Student: --- Teacher: - Actually, it can. Some species use sudden flashes of light to startle predators or "counter-illumination" to blend in with the faint light from above, making them invisible from below. A) Does this light come from the fish's skin or from bacteria living on them? B) So, the light is never used as a way to protect the fish from being eaten? C) Are there any land animals that use a similar glowing mechanism? D) How deep do these fish have to go before the sunlight disappears completely? E) Can these fish turn their lights off when they want to go to sleep?
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Step by Step Written Solution
Hi Elif, let's solve this dialogue completion question together by looking at the logical flow of the conversation.
Dialogue Analysis
First, let's look at the student's initial question. The student asks why deep-sea fish have glowing parts in total darkness.
*Student:* *Why do certain deep-sea fish have glowing parts... in complete darkness?*
The teacher explains this is bioluminescence, used to attract prey or find a mate. Note that the teacher's explanation focuses on offensive and reproductive uses.
*Teacher:* *...used to attract prey or find a mate...*
Now, we have a missing sentence from the student, followed by the teacher's second response. This second response is the key clue.
*Student:* *----*
The teacher starts with 'Actually, it can.' This implies the student asked a 'yes or no' question about a potential capability or limit.
*Teacher:* *Actually, it can. Some species use... light to startle predators or 'counter-illumination' to blend in...*
The teacher then explains how light is used for defense, like startling predators or hiding through counter-illumination. This suggests the student's question must have doubted whether light can be used for protection.
Let's evaluate the options to find a 'yes or no' question regarding defense.
Evaluating Options
A) Does this light come from skin or bacteria?
B) So, the light is never used as a way to protect the fish from being eaten?
C) Are there any land animals...?
D) How deep do these fish have to go?
E) Can these fish turn their lights off when they want to sleep?
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